S-100

Work on a new large medium-range bomber began in the late 1950s, in response to the disappointing results obtained with the TU-22 BLINDER, which was intended to replace the TU-16 [which had not met Air Force requirements]. In 1961 the operational and technical requirements for the new airplane were approved, specifying a supersonic missile-carrier with a speed of up to 3,000 km/h [since the overseas XB-70 could fly at a speed of 3,000 km/h] and an operational range of 2000 km, capable of hitting enemy aircraft carrier battle groups out in the ocean.
The design bureaus A.N. Tupolev, A.S. Yakovlev and P.O.Sukhoi competed for the project, and the results were summed up at the scientific and technical council held in July 1962. The Tupolev design bureau submitted the "aircraft 135" project, whose take-off weight equalled 190 tons. The design failed to match its cruising speed to that of the required one, i.e. 2,500 km/h instead of 3,000 km/h. Yakovlev proposed the Yak-35 aircraft, which resembled the American Hustler, with a take-off weight of 90 tons and a cruise speed of 3,000 km/h. The T-4/S-100 design submitted by KB Sukhoi was selected, with the support of the military and the State Committee Scientific and Technical Council.

The initial design developed in 1964 called for a tailless delta-wing aircraft with four turbojet engines placed in a single "gondola" under the fuselage. The wing had a break in the leading edge, and a small forward stabilizer was included. The plane was to be equipped with three controlled H-45 solid-fuel missiles, located under the fuselage. KB Rybinsk developed the RD-36-41 engines under the direction of P.A. Kolesov. Initially KB Sukhoi was in charge of the project, but ultimately KB Raduga took over the task. During the design process, the arrangement of the aircraft engines was modified and the number of missiles was reduced to two. Construction made extensive use of titanium and steel alloys, and the T-4 used an advanced electrohydraulic, quadruple redundancy fly-by-wire system. It was fitted with a 'droop snoot' that offered good visibility in the landing configuration, but when the nose of the aircraft was up and locked, the pilots had no forward visibility and all flying was on instruments.

The final design was 44.5m long, had a wing span of 22m, a wing surface of 295.7 square meters and a lift-off weight of 114 tons. The calculated flight-characteristics indicated that the bomber would have a range of 6000 km, a maximum speed of 3200 km/hr at an altitude of 20,000-24,000 meters and an absolute ceiling of 25,000-30,000 meters.

In December 1966, the Sukhoi design bureau presented the Air Force with the mock-up of the T-4 strike/reconnaissance aircraft. In 1967, the Soviet government issued a decree ordering an experimental batch of seven T-4 aircraft to be built, of which one should be used for static research and the rest to be flight-tested. A mock-up airplane was built in 1968, and construction of the first prototype began in 1969 at the Series Production Plant 82 in Tushino (Moscow). The first flight of the prototype T-4 took place on 22 August 1972 and subsequently the plane made 10 flights which were completed in 1974. During these flight trials the plane reached an altitude of 12,100 meters high and a speed of Mach 1.28. It is believed that the 'aircraft 101' that set a Mach 1.89 record over 2,000 km closed circuit was a T-4.

Soon after testing began, preparation for construction of the first pilot batch of planes was begun. In 1974, work on the T-4 bomber was cancelled, given the beginning of serial production of the more conventionally designed TU-22M bomber.

Although frequently compared to the American XB-70 intercontinental strategic bomber, which it superficially resembled, the T-4 medium bomber was a rather smaller aircraft intended as a medium-range theater system.

Between 1967-1969, KB Sukhoi also developed a design for the rather larger variable-geometry T-4M strategic bomber, derived from the basic T-4 design. On 10 January 1969 the Minister of Aviation Industry issued an order for research and development of a strategic supersonic bomber. A competition was initiated among the aircraft design bureaus of Tupolev, Myasishchev and Sukhoi. In 1969 and 1970 Sukhoi designed the T-4MS bomber that also had variable wings and which was entered into this competition for building a supersonic strategic bomber. The work proceeded slowly, and the T-4MS design effort was ended in favor of work on the Su-27 and other high priority tactical aircraft. In 1975 the contest between Myasishchev's M-18 design [resembling the B-1 in appearance] and Tupolev's Tu-160 was decided in favor of Tupolev.